1. Field of the Invention
The present invention relates generally to the detection or treatment of cancer, and more specifically, prostate cancer. In particular, an antigen is shown to be associated with prostate cancer, and is useful for new methods and compositions for diagnosing or treating prostate cancer including in individuals with prostate cancer who test negative for Prostate Specific Antigen (PSA).
2. Description of the Related Art
Each year over 300,000 men are diagnosed with prostate cancer in the U.S. alone. It is the most prevalent form of cancer for men of all races. Both the incidence of prostate cancer and its associated mortality have been increasing over the past ten years. It is estimated that about 50-65% of the prostate cancer is localized, 9-17% has spread to an area near the prostate and 20-25% has metastasized to other parts of the body. Screening for prostate cancer is primarily by PSA (a blood test for Prostate Specific Antigen) and DRE (Digital Rectal Exam) testing. Confirmation of cancer is by biopsy. Treatment options depend on disease progression and include surgery, radiation and hormonal manipulation. Chemotherapy has not proven to be successful in the past, but is being tested in combination with other treatments.
As noted above, prostate cancer is currently detected by screening for prostate specific antigen (PSA) and a digital rectal exam (DRE). Neither methodology can differentiate between benign disease and cancer. The failure to differentiate can result, for example, in exposure of patients with benign disease to treatments that are unnecessary and have side effects (e.g., impotency). Moreover, it is estimated that PSA testing misses 20%-30% of all individuals with cancer. There is a clear need for a diagnostic with better sensitivity and specificity.
Furthermore, there is a critical need for therapies that can target prostate cancer cells. Ideally, these types of treatments would have application to both early stage, confined prostate cancer as well as in the treatment of metastatic disease.
In addition, an objective, quantitative measurement of the biochemical target by either demonstrating prostate cancer cell expression and/or measurement in patient specimens would expedite all phases of the therapeutic development, regulatory approval process as well as provide a rationale to stratify patients into more effective treatment groups.
Due to the difficulties in the current approaches to the detection and treatment of prostate cancer, there is a need in the art for improved methods and compositions. The present invention fulfills this need, and further provides other related advantages.